Consumer products are required to adhere to EMI/RFI (electromagnetic interference/radio frequency interference) regulations to reduce emissions and interferences from electromagnetic and RF (radio frequency) sources. EMI/RFI may be any disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. There is a very large industry involving EMI/RFI regulations compliance testing and/or mitigation. There is also some concern among consumers about potential health hazards associated with electromagnetic and radio frequency emissions from electronic products. Electronic products and systems are typically required to pass EMI/RFI testing to ensure that they do not pollute any components, devices, or persons in their vicinity. For example, EMI/RFI must be mitigated for cellular technology manufacturers, data service providers, computer manufacturers, aerospace systems, automotive industry, military electronics, appliance manufacturers, medical devices, and toy/video game manufacturers, among many others.
Digital circuits (e.g. a digital processor or other logic element) generally operate on signal waveforms having a square shape (e.g. a sequence of pulses having rising and falling edges which are generally square or rectangular in shape). When such square waveforms are generated, transmitted, received or otherwise used by a digital processor or other logic element, the square edges may produce spurious signals over a wide range of frequencies. Such broadband spectral content can make its way back to other components, such as sensors, actuators, and analog signal conditioners. This extraneous and unwanted spectral content often limits or degrades sensor/actuator performance. Extraneous content can make its way to sensitive electronics generally in at least two ways. First, via conducted paths, such as power supplies, grounds, etc., and second, via radiated paths, such as crosstalk, EMI, etc. Safeguarding against these sources of ingress can often be very challenging.
Systems containing sensors (of any type) are particularly susceptible to EMI/RFI emissions, for example from conductive paths or radiative paths. Even systems not containing sensors are usually required to pass EMI/RFI testing to ensure that such systems do not pollute other systems or subsystems through electromagnetic or radio frequency emissions. Electrical interference from one sub-system (often digital) can degrade the performance of another (often a sensor or an analog component).
It would, therefore, be desirable to provide a digital logic family with intrinsically low EMI/RFI emissions.